Die



Aug 1 l, 1 925.

2 Sheets-Sheet 1 DIE Filed Mag; 20, 1920 A. W M CURDY 37w 11km flrifz zzr Milal ing],

2 Sheets-Sheet 2 Aug. 11, I925.

A. W M CURDY DIE I Filed May 20, 1920 MMLK A Patented Aug. ll, 1925.

up: a r e ARTHUR W. MCC'UBDY, OF VICTORIA, BRITISH CQLUMBIA, CANADA; HATTIE MACE IVLCCUBDY EXECUTRIX 0F SAID ARTHUR JV. MCCURDY, DECEASED.

DIE.

Application filed May 20, 1920. Serial No. 382,993.

To all whom it may concern:

Be it known that I, ARTHUR W. MGCURDY, a subject of the King or Great Britain, residing at Victoria, British Columbia, Dominion of Canada, have invented certain new and useful lmproven'ients in Dies, of which the following is a specification.

My invention pertains to an improvec die, and more specifically it pertains to a die adapted t produce from a. flat bar or flat piece of stock a twisted or spiral membe" designed for use in the prodwtion of a bit or auger. The die ma be said to comprise a body having an bore or opening extending therethrcugh with a pair of oppositely disposed spiral grooves med in the wall of the bore or opening, the grooves, by preference, decreasing in pitch from one end of the die toward the other. in the broader aspect of the invention the grooves may be either of a continuous pitch or of a graduated pitch. By such formation 1 am enabled to free a flat bar or blank piece of stool: endwise through the die and cause it to be uniformly twisted so that as it emerges from the die it will take a true spiral form with the edges of the bar or stool: standing at an angle of approximately 32-3 to the transverse axis of the blank.

In the preferred embodiment of the invention a sh die alone will be employed to produce the blank having the desired degree of angularity, but itis conceivable that a plurality of dies acting successively may be employed. Again, in the preferred embodiment of the invention the spiral grooves adjacent the discharge end of th die, or the finishing die, as the case may be, will have the same pitch throughout an appreciable distance in order to form a finish die section which insures proper fo mation of the spiral and in a mea sure relieves the discharge end of the die from undue wear or strain, thus prolonging its life.

The invention is illustrated in the a11- nexed drawings, wherein two embodiments are shown in which,

Figure 1 is a side elevation of the interior member or element in which the spiral grooves are formed;

Fig. 2: a similar view, the member having been given a quarter turn;

Fig. 3 a vertical sectional view of such element;

Fig. i a side elevation of the body or outer element of the die;

Fig. 5 a longitudinal sectional view showing the inner and outer elements as assembled preparatory to their being secured together preferably by welding;

Fig. 6 a similar view showing the die in its completed form with the ends of the tubes or body I'll6HFlJCIS removed or cut away so as to expose the ends of the grooves at the intake and discharge ends of the die;

Fig. '7 a sectional elevation showing the die and a piece of stock passed therein, a portion thereof being completely twisted and protruding beyond the end of the die;

Fig. 8 a sectional view taken on the line VlllVHl of F '7';

Fig. 9 a plan view of a template employed in laying out the spirals upon the inner member; and

Fig. 10 a longitudinal sectional elevation showing two die elements mounted in a holder and through which the stock is advanced, the holder being likewise applicable for clamping or holding a single die, as, for instance, that shown in Fig. 6.

Referring to Figs. 1 to 9 inclusive of the drawings, 1 denotes the inner die member which is tubular in. form and has two oppositely disposed slots 2 and 3 formed therein. These slots may be readily produced by first drilling hole diametrically through the tube near one end thereof and then replacing the drill by a milling tool whereupon the tool is advanced longitudinally of the tube and the tube is simultaneously rotated about its. axis so that the milling tool Will produce two dian'ietrically opposed slots. As the milling tool is advanced th tube is given a gradual increased speed of rotation about its axis which causes the milling cutter to follow the spiral line which is laid out upon the tube so as to produce the desired spiral formation which the walls of the slots are designed to have. The reverse of this operation may be effected by starting the milling tool at the opposite end of the spiral, or the tube may be both advanced and rotated while the milling tool rotates about a fixed axis. Such spiral formation will have a decreased pitch, but, preferably, adjacent that portion which is to become the discharge end of the die the angle of the pitch will be constant.

Stated in another way, the slots will have a decrement of angular pitch except adjacent the discharge portion as just noted, and such decrement will preferably be constant. By employing a template such as shown in Fig. 9, which may be wrapped about the tubular member, and pricking therethrough onto the face of the tube, the center line of the slots may be readily depicted.

As will be seen upon reference to Figs. 1, 2 and 3, the slots thus formed stop short of the ends of the tubular member, leaving end sections a and 5, in order to maintain the sections formed between the slots in the position where they may be readily handled and to keep the walls of the slots in proper spaced relation which otherwise could not be definitely retained if the slots extended from end to end ofthe tubular member 1, thus producing two separate sections.

. The outer or body member, as it may be termed, of the die, is shown a separate element in Fig. 1, and likewise takes the form of a tubular member, as 6, the bore of which is of a diameter to make a close fit with the exterior face of the member 1 when. the parts are nested. Said member 6 has formed in it. and extending lengthwise thereof, two oppositely disposed spiral slots 7 and 8, the angularity or pitch of the slots being); the same as that of the slots formed in theelement 1 and of a width such that when the parts 1 and 6 are nested the slots 7 and S will cover the solid sauces or walls between the'slots 2 and 3 but not quite cominc-5 to the edges of said slotsl and 8. In other words. there will be a slight overlap of the solid portions of the element 1 with reference to the solid portions'of the element When thus positioned the slots 7 and 8 are filled with a suitable flux and amalgam and subjected to welding temperature which will cause such amalgz amto melt and effect a weldino union with the adjacent faee of the member 1 and the walls of the slots 7 and 8. The members 1 and 6 thus become in effectone integral structure wi h the solid portions the member (3 forming an outer wall for the slots 2 and 3, which thus become in ef ect grooves. When thus welded together the end sections t and of the member 1 and the corresponding end sections 9 and 10 of the outer body portion (3 are cut off on the lines A-A and B-B n Fig. 5, thus producing the completed die, as shown in Fig. 6.

B this method I am enabled to rapidly and cheaply produce a die having upon its interior face two diametrically disposed spiral grooves or channels, the pitch of which gradually decreases from the intake end toward the discharge end or toward that portion of the discharge end where the pitch becomes constant to produce a finishing section, as above referred to.

In Fig. 7 the die is illustrated in section with a piece of stock being forced therethrough. The stock is entered at the upper end of the die and by applying pressure to the upper end of the piece of stock, through any suitable means, as a ram 11, the stock is forced through the die, the edges thereof being held by the grooves and gradually twisted into the desired spi 'al forn'ration, the stock emerging from the die as indicated in said figure with the double twist and at angle of approximately 33. The stock will be pushed entirely through the die by the ram 11, such ram passing down through the centralbore or opening formed in the die, out of contact with the walls thereof. The stock, it will be noted, is merely held at its edges in the grooves, and thus friction is reduced to a minimum. Distortion of the stool: from a truly spiral form will not take place, and it has been found in'practiee that the spiral formation produced by the above operation is entirely satisfactory for the production of angers of the double twist type.

lVhile it is preferred to produce the spiral blank by the passage through a single die, the blank may be partly twisted in one die and then passed through a second die (or dies) l'iaving the angularity of. the grooves such as to produce the desired angular pitch. ln Fifi. 10 two dies are shown to effect such operation. in said figure 12 denotes the initial die. the grooves whereof have a pitch of say 60 and 13 indicates the second or finishing die wherein the spiral grooves stand at an angle of 33. Said dies abut and are placed within a die holder 14having a shoulder lfiaeainst which the forward or upper end of die 12 abuts, said die being held thereagainst by thelower die 13 which is forced upwardly by a hollow plug or nut 16 which is screwed into the lower end of the holder. Set screws 17 and 18 prevent rotative movement of the dies. The holder will preferably be formed with an upwardly extending tubular member 19 having oppositely disposed straight grooves 20 and 21 which aline withthe mouths of the grooves in the upper die and serve to guide the blank to said die and to maintain itiin position as it is forced into and through the dies by the ram 11. "Where a single die instead of a sectional die or a pluralityof dies is employed, a holder such as above set forth or its substantial equivalent will, of course, be employed to hold the die.

It is conceivable that the die may be formed by methods other than that above outlined, as, for instance, by a machineopparallelism eration upon the inner face of the stock to produce the grooves. In fact I have produced dies by employing a broaching tool to form the grooves but such operation is somewhat tedious and expensive and is not comparable with the method first described both as to time and expense.

Machine steel of relatively low carbon content will preferably be employed in the production of the twisted blanks or blades as it may be twisted without fracture and with minimum expenditure of power. A spiral formed of such material in the manner above set forth will be subjected to after treatment to bring about proper carbonization and temper, but no claim is made herein to such step as that forms the basis of a separate application filed on or about the 20th day of May, 1920 Serial No. 382,994.

What is claimed is:

l. A forming die for producing twisted stock, comprising a body having an axial bore or opening extending therethrough with a pair of oppositely disposed spiral grooves formed in the inner wall thereof the side faces whereof stand in approximate throughout and extend inwardly at substantially right angles to the axis of the die, said grooves decreasing in pitch from one end toward the other.

2. A die for forming spirally twisted stock from flat bar comprising a body having a cylindrical bore extending longitudinally therethrough with a pair of diametrically disposed grooves formed in the wall of the bore, said grooves having a spiral conformation gradually decreasing in pitch from the intake toward the discharge end of the die.

3. A forming die for producing spirally twisted stock comprising a body having an axial bore or opening extending therethrough with a pair of oppositely disposed spiral grooves formed in the inner wall thereof the side faces whereof stand 1n approximate parallelism throughout and extend inwardly at substantially right angles to the axis of the die, said grooves decreasing in pitch throughout the major portion of the die and terminating-tin a. finishing section wherein the grooves have an angularity of approximately 33.

4. Means for producing a spirally twisted blade from flat bar-like blanks, comprising, in combination, a holder having diametrically opposed straight guide grooves for such flat stock, a die having a bore or opening extending therethrough, said die having diametrically opposed graduated spiral grooves formed in the inner wall thereof the side faces of the grooves lying in substantial parallelism throughout, the mouths of said grooves alining with the guide grooves formed in the holder; and means acting upon the rear end of the stock to force the same into and completely through the die.

5. Means for producing a spirally twisted blade from flat bar-like stock, comprising, in combination, a holder; a die mounted in said holder, said die having a bore extending longitudinally therethrough with a pair of oppositely disposed graduated spiral grooves formed in the walls of said bore the side faces of the grooves lying in substantial parallelism throughout, the mouths of said grooves alining with a pair of diametrically disposed slots formed in the holder and serving as guides for the flat bar stock; means for securing said die in the holder; and means acting upon the rear end of the stock to force the same into and completely through the die.

In testimony whereof I have signed my name to this specification.

ARTHUR W. MoCURDY. 

